Multi-band device with reduced band loading

ABSTRACT

In an embodiment, an apparatus includes a first radio frequency (RF) signal path and a second RF signal path. The first RF signal path can provide a first RF signal when active and the second RF signal path can provide a second RF signal when active. The second RF signal path can include a matching network with a load impedance configured to prevent a resonance in the second RF signal path due to coupling with the first RF signal path when the first RF signal path is active.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/470,729, filed Mar. 27, 2017 and titled “MULTI-BAND DEVICE WITHREDUCED BAND LOADING,” which is a continuation of U.S. patentapplication Ser. No. 14/855,103, filed Sep. 15, 2015 and titled“MULTI-BAND DEVICE WITH REDUCED BAND LOADING,” which claims the benefitof priority under 35 U.S.C. § 119(e) of U.S. Provisional PatentApplication No. 62/051,191, filed Sep. 16, 2014 and titled “MULTI-BANDDEVICE WITH REDUCED BAND LOADING,” the disclosures of each which arehereby incorporated by reference in their entireties herein. Thisapplication is also related to U.S. patent application Ser. No.14/855,141 filed on Sep. 15, 2015 and titled “MULTI-BAND DEVICE HAVINGSWITCH WITH INPUT SHUNT ARM,” the disclosure of which is herebyincorporated by reference in its entirety herein.

BACKGROUND Technical Field

This disclosure relates to electronic systems and, in particular, toradio frequency (RF) circuits.

Description of the Related Technology

A large number of mobile devices are supporting communications withinmultiple frequency bands, such as frequency bands defined by a Long TermEvolution (LTE) standard. A radio frequency (RF) signal path associatedwith one frequency band can be active while another RF signal pathassociated with another frequency band can be non-active. For instance,each signal path can include a power amplifier configured to provide anRF signal within a different frequency band, an associated matchingnetwork, and an associated select switch. In this example, when a poweramplifier of a first RF signal path is active, it can provide arelatively high powered RF signal to a select switch by way of amatching network. As components for mobile devices are beingminiaturized, it can be more difficult to isolate signals from differentRF signal paths and coupling from one signal path to another can resultin insertion loss in an active RF signal path.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is an apparatus that includes a firstradio frequency (RF) signal path and a second RF signal path. The RFsignal path is configured to provide a first RF signal when active. Thesecond RF signal path is configured to provide a second RF signal whenactive. The second RF signal path includes a matching network with aload impedance configured to prevent a resonance in the second RF signalpath due to coupling with the first RF signal path when the first RFsignal path is active.

The load impedance of the matching network can prevent the resonance inthe second RF signal path due to coupling with the first RF signal pathwhen the second RF signal path is non-active and the first RF signalpath is active. The resonance can be an LC resonance of the matchingnetwork. The first RF signal and the second RF signal can be indifferent frequency bands.

The first RF signal path can include a first power amplifier configuredto provide the first RF signal and the second RF signal path can includea second power amplifier configured to provide the second RF signal.

The second RF signal path can include a select switch configured toselectively provide the second RF signal to an output of the second RFsignal path. The select switch can be a multi-throw switch. Each of thethrows of such a multi-throw switch can include a switch arm and a shuntarm electrically coupled to the respective switch arm. In an embodiment,the select switch can have a selected switch arm on and a selected shuntarm on when the second RF signal is non-active and the first RF signalpath is active, in which the impedance from the selected switch arm andthe selected shunt arm being on can contribute to the load impedance. Inan embodiment, the load impedance can include an input shunt arm andpassive impedance element in series between input of select switch andground. The passive impedance element can be, for example, a resistor.According to an embodiment, the load impedance can include a shuntcapacitor having a first end and a second end, the first endelectrically coupled to an input of the select switch, and the secondend electrically coupled to a ground potential.

Another aspect of this disclosure is an apparatus that includes a firsttransmission path and a second transmission path. The first transmissionpath includes a first power amplifier configured to provide a first RFsignal, a first matching network, and a first multi-throw switchconfigured to receive the first RF signal by way of the first matchingnetwork. The second transmission path includes a second power amplifierconfigured to provide a second RF signal that is within a differentfrequency band than the first RF signal, a second matching network, anda second multi-throw switch configured to receive the second RF signalby way of the second matching network. The second multi-throw switch hasan input impedance configured to prevent a resonance in the secondtransmission path due to coupling with the first transmission path whenthe first transmission path is active.

The input impedance of the second multi-throw switch can include apassive impedance element in series with an input shunt arm. The passiveimpedance element can include a resistor.

The input impedance of the second multi-throw switch can include a shuntcapacitor.

The second multi-throw switch can implement at least a portion of theinput impedance by having both a switch arm and a shunt armcorresponding to a selected throw on when the second multi-throw switchis in a non-active state.

Another aspect of this disclosure is apparatus that includes anamplifier configured to amplify a radio frequency (RF) signal, amatching network coupled to an output of the amplifier, and a selectswitch in communication with the amplifier by way of the matchingnetwork. The select switch is configured to electrically couple an inputof the select switch to a selected output path in an active state. Theselect switch has an input impedance in a non-active state to prevent aresonance on the matching network due to coupling to another RF signalpath from developing when the select switch is in the non-active stateand the amplifier is deactivated.

The matching network can include capacitors and inductors. The selectswitch can be a multi-throw switch having a shunt arm and a switch armcorresponding to each of the throws. Each of the throws of themulti-throw switch can be associated with different frequency bands. Theselect switch can have both the switch arm and the shunt armcorresponding to a selected throw on when the select switch is in thenon-active state. A switch control circuit can provide control signalsto the select switch to set the select switch in the non-active state.

The select switch can include an input shunt arm at the input of theselect switch, in which the input shunt arm is configured to be on whenthe select switch is in the non-active state. A passive impedanceelement can be in series with the input shunt arm between the input ofthe select switch and a ground potential.

The apparatus can include a shunt capacitor having a first end and asecond end, the first end coupled to the input of the select switch, andthe second end coupled to a ground potential.

The amplifier can be a power amplifier. The apparatus can be configuredas a power amplifier module that includes a first path configured toprovide an RF signal in a first defined frequency band and a second pathconfigured to provide an RF signal in a second defined frequency band,in which the first path includes the power amplifier, the matchingnetwork, and the select switch. The first path can be deactivated whenthe second path is activated. The second path can include a second poweramplifier, a second matching network coupled to an output of the secondamplifier, and a second select switch in communication with the secondpower amplifier by way of the second matching network. The second selectswitch can have a second input impedance when the second select switchis in a non-active state to prevent a second standing wave fromdeveloping when the second select switch is in the non-active state.

Another aspect of this disclosure is an apparatus that includes anamplifier configured to amplify a radio frequency (RF) signal, amatching network coupled to an output of the amplifier, and amulti-throw switch in communication with the amplifier by way of thematching network. The multi-throw switch is configured to have both aswitch arm and a shunt arm associated with a selected throw on in anon-active state.

Another aspect of this disclosure is an apparatus that includes a firsttransmission path and a second transmission path. The first transmissionpath includes a first power amplifier configured to provide a first RFsignal, a first matching network, and a first multi-throw switchconfigured to receive the first RF signal by way of the first matchingnetwork. The second transmission path includes a second power amplifierconfigured to provide a second RF signal that is within a differentfrequency band than the first RF signal, a second matching network, anda second multi-throw switch configured to receive the second RF signalat an input by way of the second matching network. The secondmulti-throw switch has a passive impedance element in series with aninput shunt arm between the input of the multi-throw switch and a groundpotential.

The passive impedance element can include a resistor. When the shunt armis on, a combined impedance of the passive impedance element and theshunt arm can be approximately 50 Ohms at a fundamental frequency of thefirst RF signal.

The input shunt arm can be on when the second transmission path is in anactive state. The input shunt arm can be on when the first transmissionpath is in an active state.

The apparatus can be configured as a module that includes a packageenclosing the first and second transmission paths. Such a module can bea power amplifier module and/or a multi-chip module. The apparatus canbe configured as a mobile device that includes the first and secondtransmission paths and an antenna, in which the antenna configured totransmit the first RF signal when the first transmission path is in anactive state.

Another aspect of this disclosure is an apparatus that includes a firstradio frequency (RF) signal path and a second RF signal path. The firstRF signal path is configured to provide a first RF signal when active.The second RF signal path is configured to provide a second RF signalwhen active. The second RF signal path includes a select switch havingan input shunt arm electrically coupled to an input of the selectswitch. The input shunt arm is configured to be on when the first RFsignal path is active and the second RF signal path is inactive.

The input shunt arm can be in series with a passive impedance elementbetween the input of the select switch and a ground potential. Thepassive impedance element can include resistor. The second RF signalpath can include a power amplifier configured to generate the second RFsignal when the second RF signal path is active and a matching networkconfigured to provide the second RF signal to the select switch. Thefirst RF signal and the second RF signal can be in different frequencybands. The apparatus can be configured as an electronic component for amobile device.

Another aspect of this disclosure is an apparatus that includes anamplifier configured to amplify a radio frequency (RF) signal, amatching network coupled to an output of the amplifier, and amulti-throw switch in communication with the amplifier by way of thematching network. The multi-throw switch has an input shunt armelectrically coupled to an input of the multi-throw switch. The inputshunt arm is configured to be on when the multi-throw switch is in anon-active state.

The input shunt arm can be in series with a passive impedance circuitbetween the input of the multi-throw switch and a ground potential. Thepassive impedance circuit can be a resistor. The passive impedanceelement can be in series between the input shunt arm and the input ofthe multi-throw switch.

The multi-throw switch can include at least four throws. The amplifiercan be a power amplifier.

The apparatus can further include another RF signal path that includes asecond amplifier and a second multi-throw switch configured to receive asecond RF signal from the second amplifier by way of a second matchingnetwork, in which the other RF signal path provides coupling to thematching network.

Another aspect of this disclosure is an apparatus that includes anamplifier configured to amplify a radio frequency (RF) signal, amatching network coupled to an output of the amplifier, and amulti-throw switch in communication with the amplifier by way of thematching network. The multi-throw switch has a shunt capacitor at aninput of the multi-throw switch.

Another aspect of this disclosure is an apparatus that includes a firstpath configured to provide a first radio frequency (RF) signal, and asecond path configured to provide a second RF signal. The second RFsignal is within a different frequency band than the first RF signal.The second path is configured to be deactivated when the first path isactivated. The second path includes a select switch configured toselectively provide the second RF signal to an output. The select switchhas an input impedance when the second path is deactivated to prevent astanding wave from developing when the second path is deactivated andthe first path is activated.

Another aspect of this disclosure is an apparatus that includes anamplifier configured to amplify a radio frequency (RF) signal, amatching network coupled to an output of the amplifier, the matchingnetwork including at least one capacitor and at least one inductor, anda select switch in communication with the amplifier by way of thematching network. The select switch has an input load configured toreduce an LC resonance of the matching network when the select switch isin a non-active state.

Another aspect of this disclosure is an apparatus that includes a firstpath configured to provide a radio frequency (RF) signal and a secondpath configured to be non-active when the first path is active. Thesecond path includes a matching network with a load impedance configuredto prevent a resonance in the second path due to coupling with the firstpath when the second path is non-active and the first path is active.

Another aspect of this disclosure is an apparatus that includes a firstpath configured to provide a first radio frequency (RF) signal and asecond path configured to provide a second RF signal. The second pathincludes a matching network with a load impedance configured to preventa resonance in the second path due to coupling from the first path whenthe second path and the first path are both active.

The matching network can be an LC network. The resonance can be an LCresonance of the matching network.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the inventions have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment of the invention.Thus, the inventions may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other advantages as may be taughtor suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of a front end architecture havingtransmission paths for a plurality of frequency bands.

FIG. 2A is a schematic diagram of an active band and a non-active bandwith a standing wave resonance. FIG. 2B is a graph illustratinginsertion loss curves for an active pass band of FIG. 2A with bandloading and the same active pass band without band loading.

FIG. 2C is a schematic diagram of a radio frequency (RF) signal paththat can reduce band loading according to an embodiment.

FIG. 2D is a schematic diagram of another RF signal path that can reduceband loading according to an embodiment.

FIG. 3A is a schematic diagram of an active band and a non-active bandwith a band select switch configured to reduce band loading according toan embodiment.

FIG. 3B is a graph illustrating insertion loss curves for an active passband in accordance with the embodiment of FIG. 3A and an active passband without band loading.

FIG. 4A is a schematic diagram of an active band and a non-active bandwith a shunt switch at an input of a band select switch according to anembodiment. FIG. 4B is a graph illustrating insertion loss curves for anactive pass band in accordance with the embodiment of FIG. 4A and anactive pass band without band loading.

FIG. 5A is a schematic diagram of an active band and a non-active bandwith a shunt capacitor at an input of a band select switch according toan embodiment. FIG. 5B is a graph illustrating insertion loss curves foran active pass band in accordance with the embodiment of FIG. 5A and anactive pass band without band loading.

FIG. 6A is a schematic diagram of an active band and a non-active bandwith a shunt with a shunt switch in series with a passive impedancecircuit at an input of a band select switch according to an embodiment.FIGS. 6B to 6G illustrate example passive impedance circuits of FIG. 6A.

FIG. 7 is a schematic block diagram of an example power amplifier modulethat that include transmission paths in accordance with any of theembodiments of FIGS. 3A, 4A, 5A, and/or 6A.

FIG. 8 is a schematic block diagram of an example mobile device thatthat include transmission paths in accordance with any of theembodiments of FIGS. 3A, 4A, 5A, and/or 6A.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following detailed description of certain embodiments presentsvarious descriptions of specific embodiments. However, the innovationsdescribed herein can be embodied in a multitude of different ways, forexample, as defined and covered by the claims. In this description,reference is made to the drawings where like reference numerals canindicate identical or functionally similar elements. It will beunderstood that elements illustrated in the figures are not necessarilydrawn to scale. Moreover, it will be understood that certain embodimentscan include more elements than illustrated in a drawing and/or a subsetof the elements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

The deployment of mobile communication standards, such as Long TermEvolution (LTE), worldwide has provided a desire to have mobile devicessupport communications over more and more frequency bands. Within thelimited physical space of a front end module, band to band isolation isbecoming more difficult to implement. In certain power amplifier (PA)front end modules, dual band block designs have been adopted forrelatively easy routing with a minimal footprint. Front end modules inmobile devices that support communications over several frequency bandscan be built from several dual band blocks due to limited availablephysical space and relative ease of integration.

In such a dual band PA, one band can be active and transmitting arelatively high power signal while the other band can be non-active(e.g., shut off by a switch). As used herein, “active band” can refer tocircuitry of an RF signal path that is in an active state and providingan RF signal within a defined frequency band. As used herein,“non-active band” can refer to circuitry of an RF signal path that is anon-active state and not providing an RF signal. The non-active band canpick up signals from the active band due to coupling between the twobands. Such a band to band coupling can also be referred to as bandloading. Band loading is one problem in a multi-band PA design, such asa dual band PA design. Band loading can involve the existence of one ormore non-active bands in a relatively close proximity in frequency to anactive band that cause energy losses in the active pass band, such asactive pass band suck out. For instance, when operating at a frequencywhere the non-active band PA output path can form a standing waveresonance, the active band can couple non-trivial energy into thenon-active band. This can lead to energy suck out in the active band.Band loading can thus impact the insertion loss of the active band.

In an illustrative example, a PA output matching network can beconnected to a band select switch. The band select switch inputimpedance for a non-active state, which can also be referred to as anoff state, can provide a high impedance which can allow a standing waveto exist on this non-active band PA output path. When the standing waveis formed, it can suck out energy from the active band and cause bandloading on the active band.

Band loading can be reduced by keeping a relatively large physicaldistance between circuitry of the active band and circuitry of anon-active band. Band loading can also be reduced by shielding circuitryof one band from circuitry of another band. Such approaches typicallyconsume extra physical space. This can undesirably increase the sizeand/or footprint of a module. In turn, the increased size and/orfootprint can make it difficult and/or unfeasible to integrate circuitryfor more bands into one mobile device.

Aspects of this disclosure relate to providing a non-active band loadimpedance to reduce or eliminate band loading without significantlyimpacting other PA performance parameters. A non-open impedance at thenon-active band load side can be provided to reduce reflection from theload. This can damp a standing wave amplitude in a non-active band andthereby avoid suck out in the active band. The non-open impedance can beachieved a variety of ways, such as with an off-state switch inputimpedance, with dedicated switch logic, with a relatively small shuntcapacitor at the non-active band load, or any combination thereof. Suchnon-active band load impedance control can be used in a wide variety ofproducts.

Embodiments discussed herein relate to providing a select switch inputimpedance that can prevent (e.g., reduce and/or eliminate) standingwaves in a non-active path, such as a non-active band path. When thenon-active band PA output load or the select switch input impedance isrelatively matched, standing waves should not be sustained and the bandloading should be resolved. Several approaches to modify the selectswitch input impedance for the non-active band are discussed herein. Inthese approaches, a shunt path can be provided to the select switchinput. In one embodiment, the select switch logic state of all-off canleave one switch arm on and the switch input impedance can be at avalue, such as a value selected from the range from about 10 Ohms to 30Ohms, such that the load impedance should not sustain the standing wavein the non-active band PA output path. More details regarding thisembodiment will be discussed with reference to FIG. 3A. In some otherembodiments, one shunt arm can be added to the select switch input side.In a non-active all-off state, the added shut arm can be on and forcethe select switch input impedance to a value, such as a value selectedfrom the range from about 10 Ohms to 30 Ohms, that should not sustain astanding wave on the non-active PA output path. The added input shuntarm can be arranged in series with a resistor or a passive impedancecircuit. More details regarding these embodiments will be discussed withreference to FIGS. 4A and 6A. In another embodiment, a relatively smallshunt capacitor, such as a shunt capacitor having a capacitance selectedfrom the range from about 2 pF to 8 pF, can be included at an input ofthe select switch. The added shunt capacitor should turn the standingwave wavelength and shift the suck out notch out of the active passband. More details regarding this embodiment will be discussed withreference to FIG. 5A.

Embodiments discussed herein can advantageously modify the non-activeband PA output load impedance instead of physically separatingtransmission paths associated with different bands or using the groundplane to shield transmission paths associated with different bands fromeach other. Modifying the PA output off-state load impedance inaccordance with the principles and advantages discussed herein canreduce and/or eliminate band loading issues that can occur in compact PAmodules.

While preventing a resonance, such as a standing wave resonance, in anon-active band is discussed herein in connection with certainembodiments for illustrative purposes, it will be understood that theprinciples and advantages discussed herein can be applied to reduce oreliminate a resonance in any circuit in a non-active path that canexperience coupling from an active path, such as an active band path.Modifying a load impedance of a matching network for the non-active pathcan reduce and/or eliminate such resonances.

FIG. 1 is a schematic block diagram of a front end architecture 10having transmission paths for a plurality of frequency bands. Thesetransmission paths can be RF signal paths. The illustrated front endarchitecture includes a first transmission path 12, a secondtransmission path 14, a switch module 16, and an antenna 18. The frontend architecture 10 can include more elements than illustrated in FIG. 1and/or some embodiments can include a subset of the illustratedelements. Although the front end architecture 10 may be described withreference to two transmission paths, it will be understood that theprinciples and advantages discussed herein can be applied to front endarchitectures having three or more transmission paths.

The first transmission path 12 and the second transmission path 14 canbe configured to provide radio frequency (RF) signals within differentdefined frequency bands. An RF signal can have a frequency in the rangefrom about 30 kHz to 300 GHz, such as in a range from about 450 MHz toabout 4 GHz for radio frequency signals in Long Term Evolution systems.The different frequency bands can be frequency bands defined by an LTEstandard. The different frequency bands can be non-overlapping infrequency. In an illustrative example, the first transmission path 12can be a high band path and the second transmission path 14 can be a lowband path. The first transmission path 12 can generate RF signals withindefined sub-bands of the defined frequency band of the firsttransmission path 12. The second transmission path 14 can generate RFsignals within defined sub-bands of the defined frequency band of thesecond transmission path 14. One of the first transmission path 12 andthe second transmission path 14 can be activated while the other can benon-active.

The switch module 16 can selectively electrically couple an RF signalfrom the first transmission path 12 or the second transmission path 14to the antenna 18. The switch module 16 can also selectively provide anRF signal from a selected sub-band of the first transmission path 12 orthe second transmission path 14 to the antenna 18. The switch module 16can include filters each configured to pass a particular frequency bandin an electrical path to the antenna 18. Such filters can be band passfilters. The switch module 16 can create a signal path in which a filterassociated with the selected frequency band is included between thefirst transmission path 12 or the second transmission path 14 and theantenna 18. The switch module 16 can also serve to electrically couplethe antenna 18 to a selected receive path (not illustrated). In suchinstances, duplexers with transmit and receive filters can be includedin the switch module 16.

FIG. 2A is a schematic diagram of an active band and a non-active bandwith a standing wave resonance. FIG. 2A illustrates a transmission path22 for the non-active band and a separate transmission path 23 for theactive band. Both of these transmission paths can be included in RFsignal paths. It will be understood that the active band and thenon-active band can be switched during operation of an electronic devicethat includes the transmission paths 22 and 23. The transmission path 22for the non-active band can include a power amplifier 24, a matchingnetwork 25, and a band select switch 26. The transmission path 22 forthe non-active band can correspond to the first transmission path 12 ofFIG. 1 and a portion of the switch module 16 of FIG. 1. The transmissionpath 23 for the active band can include a power amplifier 27, a matchingnetwork 28, and a band select switch 29. The power amplifier 27 canprovide an RF signal within a different frequency band than an RF signalprovided by the power amplifier 24. In addition, the matching network 28can provide impedance matching for different frequencies than thematching network 25. Accordingly, one or more passive impedance elementsof the matching network 28 can have a different capacitance orinductance than a corresponding passive impedance element in thematching network 25. According to some other embodiments (notillustrated), the matching networks for different bands can havedifferent circuit topologies and/or can provide different filteringfunctions. The transmission path 23 for the active band can correspondto the second transmission path 14 of FIG. 1 and a portion of the switchmodule 16 of FIG. 1.

Coupling between the transmission path 23 for the active band and thetransmission path 22 for the non-active band illustrated in FIG. 1 cancreate a standing wave resonance on the non-active band while the activeband transmits a RF signal. This standing resonance can lead to bandloading and thereby increase the insertion loss of the transmission path23 for the active band.

FIG. 2B is a graph illustrating insertion loss curves for an active passband with band loading and the same active pass band without bandloading. In FIG. 2B, a first curve 30 represents insertion loss of thetransmission path 23 for the active band illustrated in FIG. 2A. A notch31 is present in the first curve 30 as a result of band loading. Thenotch 31 can occur due to the standing wave resonance of a non-activeband, for example, as illustrated in FIG. 2A. The standing waveresonance can lead to suck out in the active band. In FIG. 2B, a secondcurve 32 represents the active pass band without band loading. Thesecond curve 32 has desirable insertion loss characteristics relative tothe first curve 30.

Surface current plots indicate that with a standing wave resonance asillustrated in FIG. 2A, the non-active path can sustain a significantcurrent that consumes energy and is represented in the active band as asuck out, as indicated by the notch 31 of the first curve 30 of FIG. 2A.Other surface current plots indicate that with a matched load, such as a50 Ohm load, at an input side of the band select switch 26 of thetransmission path 22 of the non-active band, the non-active path showsminimal current which should not cause a significant suck out in thetransmission path 23 for the active band.

The band loading problem illustrated in FIG. 2A can be prevented bymodifying the non-active band load impedance. For instance, thenon-active band load impedance can be implemented by a non-active switchlogic state in which the switch has at least one arm that is on asillustrated in FIG. 3A. As another example, the non-active band loadimpedance can be a finite switch input impedance in series with apassive impedance element in a non-active state as illustrated in FIG.4A and FIG. 6A. As another example, the non-active band load can beimplemented by a shunt reactance to avoid a completely open load asillustrated in FIG. 5A. As such, the non-active load impedance caninclude a relatively small shunt reactance, a selected non-active stateswitch input impedance that can be in series with a passive impedancecircuit, a dedicated switch non-active state, or any combinationthereof.

FIG. 2C is a schematic diagram of an RF signal path that can reduce bandloading according to an embodiment. As illustrated, the RF signal pathcan include a power amplifier 24, a matching network 25, and amulti-throw switch 36. The illustrated multi-throw switch 36 includes aswitch element 37 that can implement multiple throws with a switch armand a shunt arm for each throw. The switch element 37 can implement anysuitable number of throws. The RF signal path can provide an RF signalwhen active. The RF signal path can be located in relatively closephysical proximity to one or more other RF signal paths.

A load impedance of the matching network 25 can prevent a resonance onthe RF signal path due to coupling with another RF signal path inrelatively close physical proximity when the other signal path isactive. An input impedance Z of the multi-throw switch 36 can beincluded in such a load impedance on the matching network 25. In theabsence of the input impedance Z of the multi-throw switch 36, astanding wave resonance can develop on the RF signal path due tocoupling with the other RF signal path. The input impedance Z can beimplemented by setting a state of the switch element 37, for example, inaccordance with the principles and advantages that will be discussedwith reference to FIG. 3A. In some other implementations, the inputimpedance Z can be implemented by a shunt capacitor. According tocertain implementations, the input impedance Z can be implemented by aninput shunt arm and a passive impedance circuit.

FIG. 2D is a schematic diagram of an RF signal path that can reduce bandloading according to an embodiment. The RF signal path of FIG. 2D is anexample of the RF signal path of FIG. 2C in which the multi-throw switch36′ includes a shunt arm 40 in series with a passive impedance circuit60 to implement an input impedance of the multi-throw switch. The shuntarm 40 can be on when the RF signal path is inactive. Accordingly, whenthe RF signal path is inactive, the passive impedance circuit 60 can beelectrically connected to ground by way of the input shunt arm 40. Theinput shunt arm 40 can be off when the RF signal path is active. Thepassive impedance circuit 60 can be a resistor, any other suitablepassive impedance element, or any other suitable combination of passiveimpedance elements.

Embodiments of a transmission path for a non-active band are illustratedin FIGS. 3A, 4A, 5A, and 6A. In these embodiments, the transmission path22 of FIG. 2A is modified. It will be understood that one or more othertransmission paths can also implement the principles and advantagesdiscussed with reference to any of FIGS. 3A, 4A, 5A, and/or 6A. Forinstance, the one or more other transmission paths can include atransmission path for an active band. In some instances, the one or moreother transmission paths can include a transmission path for anothernon-active band that is also non-active when the illustrated non-activeband is non-active. Moreover, any combination of features of theembodiments of FIGS. 3A, 4A, 5A, and 6A can be combined with each other.During operation, different transmission paths can selectively beactivated and deactivated. Each transmission path can be in an activestate or non-active state. Accordingly, a transmission path that isdescribed herein as being non-active can be active at another point intime. Similarly, a transmission path that is described herein as beingactive can be a non-active at another point in time.

While certain embodiments are described with reference to one activeband and one active band, the principles and advantages discussed hereincan be applied to carrier aggregation applications in which two or morebands can be active concurrently. For instance, the principles andadvantages discussed herein can be applied when two active band pathscause band loading on a non-active band path. As another example, theprinciples and advantages discussed herein can be applied to preventingband loading between two active bands that can cause additionalinsertion loss from one active band to another active band. To reduceand/or eliminate band loading from one active band to another activeband, any suitable principles and advantages discussed herein can beapplied to preventing a resonance on an active band due to coupling withanother active band. For instance, a shunt capacitor and/or input shuntarm at an output of a matching network and/or at an input of a bandselect switch can prevent such a resonance on an active path.

FIG. 3A is a schematic diagram of an active band and a non-active bandwith a band select switch configured to reduce band loading according toan embodiment. The transmission path 22′ of FIG. 3A is a modifiedversion of the transmission path 22 of FIG. 2A. The transmission path22′ includes the power amplifier 24, the matching network 25, and a bandselect switch 26′. The transmission path 23′ of FIG. 3A is a modifiedversion of the transmission path 23 of FIG. 2A. The transmission path23′ includes the power amplifier 27, the matching network 28, and a bandselect switch 29′. The transmission paths 22′ and 23′ can be inrelatively close physical proximity to each other such that coupling canoccur between the transmission paths. Embodiments of any of thetransmission paths discussed herein can include more elements thatillustrated and/or a subset of the illustrated elements. Moreover, atransmission path can include any suitable combination of features ofany of the transmission paths disclosed herein.

The power amplifier 24 is configured to amplify an RF signal and providean amplified RF signal. The power amplifier 24 can be any suitable RFpower amplifier. For instance, the power amplifier 24 can be one or moreof a single stage power amplifier, a multi-stage power amplifier, apower amplifier implemented by one or more bipolar transistors, or apower amplifier implemented by one or more field effect transistors. Thepower amplifier 24 can be deactivated when the transmission path 22′ isnon-active. For instance, a bias provided to the power amplifier 24 candeactivate the power amplifier 24 when the transmission path 22′ isnon-active.

The matching network 25 can aid in reducing signal reflections and/orother signal distortions. The matching network 25 can include one ormore capacitors and one or more inductors. The matching network 25 caninclude more of a shunt capacitor, a shunt inductor, a shunt series LCcircuit, a parallel LC circuit in a signal path between the poweramplifier 24 and the band select switch 26′, a capacitor in the signalpath, or an inductor in the signal path. As illustrated by the arcs ofthe matching network 25, one or more inductors of the matching network25 can be implemented by a bond wire. While the matching network 25 isprovided for illustrative purposes, it will be understood that theprinciples and advantages discussed herein can be implemented inconnection with any other suitable matching network.

The band select switch 26′ is coupled to the power amplifier 24 by wayof the matching network 25. The output of the matching network 25 can beprovided to an input of the band select switch 26′. In an active state,the band select switch 26′ can electrically couple an RF signal receivedat the input to a selected output. Different outputs of the band selectswitch 26′ can be associated with a different defined frequency bands.For instance, two different outputs of the band select switch 26′ can beassociated with two different defined sub-bands of a defined frequencyband of the transmission path 22′. The different outputs of the bandselect switch 26′ can be electrically coupled to different transmissionspaths that are associated with the different defined sub-bands. Thedifferent transmission paths can each include a filter and/or othercircuitry for processing the RF signal for transmission within arespective defined sub-band.

The band select switch 26′ and any of the other illustrated band selectswitches disclosed herein can be implemented insemiconductor-on-insulator technology, such as silicon-on-insulatortechnology. The illustrated band select switch 26′ is a multi-throwswitch. While the band select switch 26′ is shown as a single polemulti-throw switch for illustrative purposes, it will be understood thatthe principles and advantages discussed herein can be applied to RFsignal paths that include multi-pole multi-throw switches.

Each throw of the band select switch 26′ includes a switch arm and ashunt arm electrically coupled to the switch arm. The switch arm canprovide an input signal received from the matching network 25 to anoutput of the band select switch 26′ when the switch arm is on. Theswitch arm can be implemented by a field effect transistor asillustrated. The switch arm can turned on and turned off based on acontrol signal for the switch arm, such as one of the control signals A,B, C, or D illustrated in FIG. 3A. As illustrated in FIG. 3A, thecontrol signal can be provided to a gate of the field effect transistorthat implements the switch arm. The shunt arm can provide a path toground when the shunt arm is on. The shunt arm can be implemented by afield effect transistor as illustrated. The shunt arm can turned on andturned off based on a shunt control signal for the shunt arm, such asone of the shunt control signals S_(A), S_(B), S_(C), or S_(D)illustrated in FIG. 3A. As illustrated in FIG. 3A, the shunt controlsignal can be provided to a gate of the field effect transistor thatimplements the shunt arm. The shunt arm can provide suitable band toband isolation in the band select switch 26′, particularly when the bandselect switch 26′ is implemented in silicon-on-insulator technology.

The band select switch 26′ can electrically couple its input to aselected output by turning a switch arm associated with the selectedoutput on and turning a shunt arm associated with the selected outputoff. The other switch arms of the band select switch 26′ can be off andthe other respective shunt arms of the band select switch 26′ can be onwhile the input is being electrically coupled to the selected output.This can electrically isolate the input of the band select switch 26′from the non-selected outputs.

The band select switch 29′ can implement any of features discussed withreference to the band select switch 26′. While the band select switch29′ is shown in the active state, in a non-active state the band selectswitch 29′ can operate in a state similar to the illustrated state ofthe band select switch 26′. The switch control circuit 35 can operatesimilarly to the switch control circuit 34 of the transmission path 22′.

While the band select switches illustrated in FIGS. 2A, 3A, 4A, 5A, and6A include a series field effect transistor and a shunt field effecttransistor for each throw, it will be understood that in some otherembodiments a band select switch can include a series field effecttransistor without a shunt field effect transistor for some or all ofthe throws.

The power amplifier 24 of transmission path 22′ can be electricallydecoupled from an antenna, such as the antenna 18 of FIG. 1, by settingthe band select switch 26′ to a non-active state. The non-active statecan also be referred to as an off state. In the non-active state of theband select switch 26′, the band select switch 26′ electrically isolatesthe output of the matching network 25 from all of the outputs of theband select switch 26′.

In the embodiment shown in FIG. 3A, one of the switch arms is on and theremaining switch arms are off in the non-active state of the band selectswitch 26′. The shunt arm associated with the switch arm that is on isalso on in the non-active state. Having one switch arm on and theassociated shunt arm on can provide an impedance at the load side of thematching network 25 to reduce the reflection from the load and therebydamp any standing wave amplitude in the non-active transmission path22′. Accordingly, band loading on the transmission path 23′ when it isactive can be reduced and/or eliminated. In some other embodiments (notshown in FIG. 3A), two or more switch arms and their corresponding shuntarms can be on to thereby provide an impedance at the load side of thematching network 25 to prevent resonance due to coupling with an activeband.

A switch control circuit 34 can provide control signals A, B, C, D,S_(A), S_(B), S_(C), and S_(D) to the band select switch 26′. The switchcontrol circuit 34 can control the state of the band select switch 26′by providing the control signals. The control signals can set the stateof the band select switch 26′ to the non-active state when thetransmission path 22′ is non-active. The control signals can set thestate of the band select switch 26′ to an active state in which theinput of the band select switch 26′ is provided to a selected output ofthe band select switch 26′ when the transmission path 22 is active. Theswitch control circuit 34 can be implemented by any suitable circuitry.

FIG. 3B is a graph illustrating insertion loss curves for an active passband with in accordance with the embodiment of FIG. 3A and an activepass band without band loading. The curve 38 is associated with theembodiment of FIG. 3A and the curve 39 is associated with no bandingloading on the active band. As shown by the curves 38 and 39 of FIG. 3B,the embodiment of FIG. 3A works well to prevent band loading.

FIG. 4A is a schematic diagram of an active band and a non-active bandwith a shunt switch arm at an input of a band select switch according toan embodiment. The transmission path 22″ illustrated in FIG. 4A includesa power amplifier 24 and a matching network 25 that can implement anycombination of features discussed with reference to FIG. 3A. Thetransmission path 22″ of FIG. 4A includes a different band select switchthan the transmission path 22′ of FIG. 3A. In addition, relative to theswitch control circuit 34 of FIG. 3A, the switch control circuit 34′ ofFIG. 4A can provide an additional control signal and/or can providedifferent values of some signals provided to the band select switch 26″when the band select switch 26″ is in a non-active state.

The transmission path 23″ can implement any combination of features ofthe transmission path 22″. The transmission path 23″ can be in an activestate while the transmission path 22″ is in a non-active state. Thetransmission paths 22″ and 23″ can be in relatively close physicalproximity to each other such that coupling can occur between thetransmission paths.

The band select switch 26″ of FIG. 4A includes an input shunt arm 40 atthe input of the band select switch 26″. The input shunt arm 40 can beon when the transmission path 22″ is non-active and off when thetransmission path 23″ is active. When the input shunt arm 40 is on, itcan provide a shunt path. The input shunt arm 40 and a resistor 42 canbe in series between the input of the band select switch 26″ and ground.When the input shunt arm 40 is on, the input shunt arm 40 and theresistor 42 can together provide a desired matching impedance, such asapproximately 50 Ohms. As one example, the resistor 42 can have aresistance of about 44 Ohms such that the series resistance of theresistor 42 and the shunt arm 40 is about 50 Ohms when the shunt arm 40is on.

The input shunt arm 40 can be implemented by a field effect transistoras illustrated in FIG. 4A. The field effect transistor can be an N-typetransistor as illustrated. The source of the field effect transistor canbe connected to ground, the drain of the field effect transistor can beconnected to the input of the band select switch 26″, and the gate ofthe field effect transistor can receive an off state control signalS_(OFF). The switch control circuit 34′ of FIG. 4A can control the offstate control signal S_(OFF) such that the input shunt arm 40 is on whenthe transmission path 22″ is non-active and the input shunt arm 40 isoff when the transmission path 22″ is active. Alternatively, the switchcontrol circuit 34′ of FIG. 4A can control the input shunt arm 40 of thetransmission path 22″ such that the input shunt arm 40 is on when thetransmission path 23″ is active and the input shunt arm is off when thetransmission path 23″ is non-active.

The input shunt arm 40 of the band select switch 26″ can provide animpedance at the load side of the matching network 25 to reduce thereflection from the load and thereby damp any standing wave amplitude inthe non-active transmission path 22″. Accordingly, band loading on theactive transmission path 23″ can be reduced and/or eliminated.

The band select switch 29″ includes an input shunt arm 40′ in serieswith a resistor 42′. While the band select switch 29″ is shown in anactive state, in a non-active state the band select switch 29″ canoperate in a state similar to the illustrated state of the band selectswitch 26″. Accordingly, the band select switch 29″ can implement any offeatures discussed with reference to the band select switch 26″ preventan unwanted resonance on the transmission path 23″. This can cause bandloading on the transmission path 22″ in an active state (notillustrated) to be reduced and/or eliminated.

FIG. 4B is a graph illustrating insertion loss curves for an active passband with in accordance with the embodiment of FIG. 4A and an activepass band without band loading. The curve 41 is associated with theembodiment of FIG. 4A and the curve 42 is associated with no bandingloading on the active band. As shown by the curves 41 and 42 of FIG. 4B,the embodiment of FIG. 4A works well to prevent band loading.

FIG. 5A is a schematic diagram of an active band and a non-active bandwith a shunt capacitor at an input of a band select switch according toan embodiment. The transmission path 22′″ illustrated in FIG. 5Aincludes a power amplifier 24 and a matching network 25 that canimplement any combination of features discussed with reference to FIGS.3A and/or 4A. The transmission path 22′″ of FIG. 5A includes a differentband select switch than the transmission path 22′ of FIG. 3A and thetransmission path 22″ of FIG. 4A.

The transmission path 23′″ can implement any combination of features ofthe transmission path 22′″. The transmission path 23′″ can be in anactive state while the transmission path 22′″ is in a non-active state.The transmission paths 22′″ and 23′″ can be in relatively close physicalproximity to each other such that coupling can occur between thetransmission paths.

The band select switch 26′″ of FIG. 5A includes an shunt capacitor 50 atthe input of the band select switch 26′″. The shunt capacitor 50 can beconsidered part of the band select switch 26′″ even if it is implementedseparately. The shunt capacitor 50 can have a relatively smallcapacitance, such as a capacitance on the order of a few picofarads(pF). The capacitance of the shunt capacitor 50 can be selected suchthat an impedance of the shunt capacitor 50 matches a selected impedanceat a frequency of the active band. In an illustrative example, the shuntcapacitor can have a capacitance in a range from about 2 pF to 3 pF tomatch a 50 Ohm impedance in certain applications. The shunt capacitor 50can prevent a standing wave resonance on the non-active path 22′″.

As illustrated, the band select switch 29′″ of the transmission path23′″ includes a shunt capacitor 50′ that can provide the same or similarfunctionality to the shunt capacitor 50. The shunt capacitors 50 and 50′can have approximately the same capacitances in certain applications. Inother applications, the shunt capacitors 50 and 50′ can have differentcapacitances.

The switch control circuits 34″ and 35″ can provide the same or similarfunctionality as the other switch control circuits 34 and 35,respectively.

FIG. 5B is a graph illustrating insertion loss curves for an active passband with in accordance with the embodiment of FIG. 5A and an activepass band without band loading. The curve 51 is associated with theembodiment of FIG. 5A and the curve 52 is associated with no bandingloading on the active band. As shown by the curves 51 and 52 of FIG. 5B,the embodiment of FIG. 5A works well to prevent band loading. The curve51 of FIG. 5B has a notch in the insertion loss curve between about 0.60GHz and 0.65 GHz. This notch can be created by a shunt capacitor beingpresent in the signal path in the active band.

FIG. 6A is a schematic diagram of an active band and a non-active bandwith a shunt switch arm at an input of a band select switch according toan embodiment. The transmission path 22″″ illustrated in FIG. 6A issimilar to the transmission path 22″ of FIG. 4A except that a passiveimpedance circuit 60 is shown in place of a resistor 42. Accordingly,any suitable passive impedance circuit can be implemented in series withan input shunt arm 40 of a band select switch to provide an impedance toprevent (e.g., reduce or eliminate) a standing wave resonance on anon-active band due to coupling with an active band.

The passive impedance circuit 60 can be implemented by any suitablepassive impedance element(s). The resistor 42 of FIG. 4A is one exampleof a suitable passive impedance circuit 60. FIGS. 6B to 6G illustrateother examples of the passive impedance circuit 60 of FIG. 6A. As shownin FIG. 6B, a capacitor can implement a passive impedance circuit 60″.As another example, an inductor can implement a passive impedancecircuit 60′″ as shown in FIG. 6C. Suitable passive impedance circuitscan include series and/or parallel combinations of passive impedanceelements, for example, as illustrated in FIGS. 6D to 6G. A series LCcircuit can implement a passive impedance circuit 60″″ as shown in FIG.6D. A parallel LC circuit can implement a passive impedance circuit60′″″ as shown in FIG. 6E. FIG. 6F shows a series RLC passive impedancecircuit 60″″″. As one more example, a resistor in series with a parallelLC circuit can implement a passive impedance circuit 60′″″″ as shown inFIG. 6G.

Referring back to FIG. 6A, the transmission path 23″″ can implement anycombination of features of the transmission path 22″″. The transmissionpath 23″″ can be in an active state while the transmission path 22″″ isin a non-active state. The transmission paths 22″″ and 23″″ can be inrelatively close physical proximity to each other such that coupling canoccur between the transmission paths.

The band select switch 26′″ of FIG. 6A is similar to the band selectswitch 26″ of FIG. 4A except that the passive impedance circuit 60 isshown in place of the resistor 42. The band select switch 29′″ of FIG.6A is similar to the band select switch 29″ of FIG. 4A except that thepassive impedance circuit 60′ is shown in place of the resistor 42′. Thepassive impedance circuit 60′ of the transmission path 23′″ can providethe same or similar functionality to the passive impedance circuit 60.The passive impedance circuits 60 and 60′ can have the same circuittopology in certain applications. In other applications, the passiveimpedance circuits 60 and 60′ can have different circuit topologies.

The switch control circuits 34′″ and 35′″ can provide the same orsimilar functionality as the other switch control circuits 34′ and 35′,respectively.

While FIGS. 3A, 4A, 5A, and 6A illustrate examples of loads at an inputof a band select switch that can reduce an LC resonance and/or astanding wave resonance of an output matching network of a non-activetransmission path, it will be understood that other suitable loads canbe provided to prevent standing wave resonances from a matching networkthat includes capacitors and inductors.

FIG. 7 is a schematic block diagram of an example power amplifier module70 that that include transmission paths in accordance with any of theembodiments discussed herein, such as any of the embodiments discussedwith reference to FIGS. 3A, 4A, 5A, and/or 6A. The illustrated poweramplifier module 70 includes a power amplifier die 72, a matchingnetwork 74, and a switch die 76. The power amplifier module 70 can be apackaged module that includes a package encapsulating the poweramplifier die 72, the matching network 74, and the switch die 76. Thepower amplifier die 72, the matching network 74, and the switch die 76can be mounted to and/or implemented on a common substrate. The commonsubstrate can be a laminate substrate or other suitable packagingsubstrate. In some other embodiments (not shown in FIG. 7), the poweramplifier and the band select switch can be implemented on a single die.

The power amplifier die 72 can include any of the power amplifiersdiscussed herein, such as the power amplifiers 24 and/or 27. The poweramplifier die 72 can be a gallium arsenide (GaAs) die, CMOS die, or asilicon germanium (SiGe) die in certain implementations. The poweramplifier die 72 can include one or more bipolar power amplifiertransistors, such as heterojunction bipolar transistors, and/or one ormore field effect bipolar transistors.

The matching network 74 can include some or all of the circuit elementsof the matching networks discussed herein, such as the matching networks25 and/or 28. The matching network 74 can include one or more surfacemounted capacitors, one or more surface mounted inductors, one or moreinductors implemented by a spiral trace on and/or in a packagingsubstrate, one or more capacitors implemented on a separate die or aprinted circuit board, one or more inductors implemented on a separatedie or a printed circuit board, one or more bond wires the like, or anycombination thereof. As one example, the matching network 74 can includean integrated passive device (IPD) die, surface mounted capacitors,spiral inductors implemented on a substrate, and bond wires thatimplement inductors. In an embodiment (not shown in FIG. 7), a portionof the matching network, such as one or more capacitors, can beimplemented on the power amplifier die 72.

The switch die 76 can include one or more of the band select switchesdiscussed herein, such as the band select switches of FIGS. 3A, 4A, 5A,and/or 6A. The switch die 76 can include switch select logic, such asthe switch select logic discussed with reference to FIGS. 3A and/or 4A.The switch die 76 can be a manufactured with a different processtechnology than the power amplifier die 72. In certain implementations,the switch die 76 can be a CMOS die or a semiconductor-on-insulator(SOI) die, such as a silicon-on-insulator die.

While FIG. 7 relates to a power amplifier module for illustrativepurposes, transmission paths in accordance with any of the embodimentsdiscussed herein can be implemented in various modules. For instance,any of the principles and advantages discussed herein can be implementedin a multi-chip module and/or a front end module. Such modules caninclude additional circuits and/or die(s) enclosed within the samepackage as the first transmission paths. The modules can be componentsfor mobile devices such as smart phones.

FIG. 8 is a schematic block diagram of one example of a wireless ormobile device 81 that can include one or more power amplifiers and anantenna switch module. The wireless device 81 can have one or moretransmit paths 85 that implement one or more features of the presentdisclosure. For instance, the transmit paths 85 of the wireless device81 can include the transmission paths in accordance with any of theprinciples and advantages discussed with any of FIGS. 1, 3A, 4A, 5A, orFIG. 6A. As another example, any of the band select switches and/orselect switches discussed herein can be included in the switch module 16of FIG. 8. Similarly, the switch module 16 and the antenna 18 of FIG. 8can correspond to the switch module 16 and the antenna 18, respectively,of FIG. 1. Additional elements, such as any of the matching networksdiscussed herein can be disposed between the output of any of the poweramplifiers 87 and the switch module 16 of FIG. 8.

The example wireless device 81 depicted in FIG. 8 can represent amulti-band and/or multi-mode device such as a multi-band/multi-modemobile phone. By way of example, the wireless device 81 can communicatein accordance with Long Term Evolution (LTE). In this example, thewireless device can be configured to operate at one or more frequencybands defined by an LTE standard. The wireless device 81 canalternatively or additionally be configured to communicate in accordancewith one or more other communication standards, including but notlimited to one or more of a Wi-Fi standard, a 3G standard, a 4G standardor an Advanced LTE standard. Transmit paths of the present disclosurecan be implemented within a mobile device implementing any combinationof the foregoing example communication standards, for example.

As illustrated, the wireless device 81 can include a switch module 16, atransceiver 83, an antenna 18, power amplifiers 87, matching networks 25and 28, a control component 88, a computer readable storage medium 89, aprocessor 90, and a battery 91.

The transceiver 83 can generate RF signals for transmission via theantenna 18. Furthermore, the transceiver 83 can receive incoming RFsignals from the antenna 18. It will be understood that variousfunctionalities associated with transmitting and receiving of RF signalscan be achieved by one or more components that are collectivelyrepresented in FIG. 8 as the transceiver 83. For example, a singlecomponent can be configured to provide both transmitting and receivingfunctionalities. In another example, transmitting and receivingfunctionalities can be provided by separate components.

In FIG. 8, one or more output signals from the transceiver 83 aredepicted as being provided to the antenna 18 via one or moretransmission paths 85. In the example shown, different transmissionpaths 85 can represent output paths associated with different bands(e.g., a high band and a low band) and/or different power outputs. Forinstance, the two different paths shown can represent two of thedifferent transmission paths of any of the front end architecturesdiscussed with reference to FIGS. 1, 3A, 4A, 5A, and/or 6A. Thetransmission paths 85 can be associated with different transmissionmodes. One of the illustrated transmission paths 85 can be active whileone or more of the other transmission paths 85 are non-active, forexample, as discussed above. Alternatively, two or more transmissionpaths 85 can be active in carrier aggregation applications. Othertransmission paths 85 can be associated with different power modes(e.g., high power mode and low power mode) and/or paths associated withdifferent transmit frequency bands. The transmit paths 85 can includeone or more power amplifiers 87 to aid in boosting a RF signal having arelatively low power to a higher power suitable for transmission. Asillustrated, the power amplifiers 87 can include the power amplifiers 24and 27 discussed above. Although FIG. 8 illustrates a configurationusing two transmission paths 85, the wireless device 81 can be adaptedto include more than two transmission paths 85.

In FIG. 8, one or more detected signals from the antenna 18 are depictedas being provided to the transceiver 83 via one or more receive paths86. In the example shown, different receive paths 86 can represent pathsassociated with different signaling modes and/or different receivefrequency bands. Although FIG. 8 illustrates a configuration using fourreceive paths 86, the wireless device 81 can be adapted to include moreor fewer receive paths 86.

To facilitate switching between receive and/or transmit paths, theantenna switch module 16 can be included and can be used to selectivelyelectrically connect the antenna 18 to a selected transmit or receivepath. Thus, the antenna switch module 16 can provide a number ofswitching functionalities associated with an operation of the wirelessdevice 81. The antenna switch module 16 can include a multi-throw switchconfigured to provide functionalities associated with, for example,switching between different bands, switching between different modes,switching between transmission and receiving modes, or any combinationthereof. The switch module 16 can include any of the band selectswitches discussed herein.

FIG. 8 illustrates that in certain embodiments, the control component 88can be provided for controlling various control functionalitiesassociated with operations of the antenna switch module 16 and/or otheroperating component(s). For example, the control component 88 can aid inproviding control signals to the antenna switch module 16 so as toselect a particular transmit or receive path.

In certain embodiments, the processor 90 can be configured to facilitateimplementation of various processes on the wireless device 81. Theprocessor 90 can be, for example, a general purpose processor or specialpurpose processor. In certain implementations, the wireless device 81can include a non-transitory computer-readable medium 89, such as amemory, which can store computer program instructions that may beprovided to and executed by the processor 90.

The battery 91 can be any battery suitable for use in the wirelessdevice 81, including, for example, a lithium-ion battery.

Some of the embodiments described above have provided examples inconnection with power amplifiers and/or mobile devices. However, theprinciples and advantages of the embodiments can be used for any othersystems or apparatus, such as any uplink cellular device, that couldbenefit from any of the circuits described herein. The teachings hereinare applicable to a variety of power amplifier systems including systemswith multiple power amplifiers, including, for example, multi-bandand/or multi-mode power amplifier systems. The power amplifiertransistors discussed herein can be, for example, gallium arsenide(GaAs), CMOS, or silicon germanium (SiGe) transistors. The poweramplifiers discussed herein can be implemented by field effecttransistors and/or bipolar transistors, such as heterojunction bipolartransistors.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products, electronic test equipment, cellular communicationsinfrastructure such as a base station, etc. Examples of the electronicdevices can include, but are not limited to, a mobile phone such as asmart phone, a telephone, a television, a computer monitor, a computer,a modem, a hand-held computer, a laptop computer, a tablet computer, awearable computing device such as a smart watch, a personal digitalassistant (PDA), a microwave, a refrigerator, a vehicular electronicssystem such as automotive electronics system, a stereo system, a DVDplayer, a CD player, a digital music player such as an MP3 player, aradio, a camcorder, a camera, a digital camera, a portable memory chip,a washer, a dryer, a washer/dryer, a copier, a facsimile machine, ascanner, a multi-functional peripheral device, a wrist watch, a clock,etc. Further, the electronic devices can include unfinished products.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,”“include,” “including,” and the like are to be construed in an inclusivesense, as opposed to an exclusive or exhaustive sense; that is to say,in the sense of “including, but not limited to.” The word “coupled”, asgenerally used herein, refers to two or more elements that may be eitherdirectly connected, or connected by way of one or more intermediateelements. Likewise, the word “connected”, as generally used herein,refers to two or more elements that may be either directly connected, orconnected by way of one or more intermediate elements. Additionally, thewords “herein,” “above,” “below,” and words of similar import, when usedin this application, shall refer to this application as a whole and notto any particular portions of this application. Where the contextpermits, words in the above Detailed Description of Certain Embodimentsusing the singular or plural number may also include the plural orsingular number respectively. Where the context permits, the word “or”in reference to a list of two or more items is intended to cover all ofthe following interpretations of the word: any of the items in the list,all of the items in the list, and any combination of the items in thelist.

Moreover, conditional language used herein, such as, among others,“can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and thelike, unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or states. Thus, such conditional language is notgenerally intended to imply that features, elements and/or states are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/orstates are included or are to be performed in any particular embodiment.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel apparatus, methods, andsystems described herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe methods and systems described herein may be made without departingfrom the spirit of the disclosure. For example, while blocks arepresented in a given arrangement, alternative embodiments may performsimilar functionalities with different components and/or circuittopologies, and some blocks may be deleted, moved, added, subdivided,combined, and/or modified. Each of these blocks may be implemented in avariety of different ways. Any suitable combination of the elements andacts of the various embodiments described above can be combined toprovide further embodiments. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the disclosure.

What is claimed is:
 1. A multi-band device with reduced band loading,the multi-band device comprising: a first transmission path including afirst power amplifier and a first matching network configured to receivea first radio frequency signal from the first power amplifier, the firstmatching network including first inductors and first capacitors; and asecond transmission path including a second power amplifier, a secondmatching network configured to receive a second radio frequency signalfrom the second power amplifier, and a load impedance of the secondmatching network configured to damp a standing wave resonance in thesecond transmission path due to coupling with the first transmissionpath, the second matching network including second inductors and secondcapacitors, and the first radio frequency signal and the second radiofrequency signal being in different frequency bands.
 2. The multi-banddevice of claim 1 wherein the first transmission path includes a loadimpedance of the first matching network configured to damp a resonancein the first transmission path due to coupling with the secondtransmission path.
 3. The multi-band device of claim 1 wherein the firstmatching network includes a first parallel LC circuit and a first seriesshunt LC circuit.
 4. The multi-band device of claim 3 wherein the secondmatching network includes a second parallel LC circuit and a secondseries shunt LC circuit.
 5. The multi-band device of claim 1 wherein themulti-band device is configured such that the second transmission pathis non-active when the first transmission path is active.
 6. Themulti-band device of claim 1 wherein the load impedance of the secondmatching network includes a passive impedance element in series with atransistor between an output of the second matching network and a groundpotential.
 7. The multi-band device of claim 1 wherein the loadimpedance of the second matching network includes a shunt capacitor. 8.The multi-band device of claim 1 wherein the second transmission pathincludes a multi-throw switch coupled to the second power amplifier byway of the second matching network.
 9. The multi-band device of claim 8wherein the multi-throw switch is configured to couple to the secondpower amplifier to a selected output of a plurality of outputs of themulti-throw switch.
 10. The multi-band device of claim 9 wherein eachoutput of the plurality of outputs of the multi-throw switch is coupledto a different filter.
 11. The multi-band device of claim 8 wherein aswitch arm and a shunt arm of the multi-throw switch are both configuredto be on for a throw of the multi-throw switch to provide to the loadimpedance for the second matching network when the first transmissionpath is active and the second transmission path is non-active.
 12. Amethod of multi-band radio frequency signal amplification with reducedband loading, the method comprising: amplifying a first radio frequencysignal with a first power amplifier of a first transmission path, thefirst radio frequency signal being in a first frequency band; damping,using a load impedance of a matching network of a second transmissionpath, a standing wave resonance in the second transmission path due tocoupling with the first transmission path during said amplifying thefirst radio frequency signal and while the second transmission path isnon-active; and amplifying a second radio frequency signal with a secondpower amplifier of the second transmission path, the second radiofrequency signal being in a second frequency band, and the secondfrequency band being different than the first frequency band.
 13. Themethod of claim 12 further comprising turning on a transistor that is inseries with a passive impedance element between an output of thematching network of the second transmission path and ground, the loadimpedance including a series impedance of the passive impedance elementand the transistor, and said damping being performed while thetransistor is on.
 14. The method of claim 12 further comprising settinga state of a multi-throw switch such that a shunt arm and a switch armof a throw of the switch are both on to provide the load impedance, saiddamping being performed while the shunt arm and the switch arm of thethrow of the multi-throw switch are both on.
 15. The method of claim 12wherein first matching network includes a parallel LC circuit and aseries shunt LC circuit.
 16. The method of claim 12 further comprisingcoupling the matching network to a filter using a multi-throw switchhaving outputs each coupled to a different filter.
 17. A multi-bandwireless device with reduced band loading, the multi-band wirelessdevice comprising: a first transmission path including a first poweramplifier and a first matching network configured to receive a firstradio frequency signal from the first power amplifier, the firstmatching network including first inductors and first capacitors; asecond transmission path including a second power amplifier, a secondmatching network configured to receive a second radio frequency signalfrom the second power amplifier, and a load impedance of the secondmatching network configured to damp a standing wave resonance in thesecond transmission path due to coupling with the first transmissionpath, the second matching network including second inductors and secondcapacitors, and the first radio frequency signal and the second radiofrequency signal being in different frequency bands; an antenna; and aswitch module configured to selectively electrically couple the firsttransmission path to the antenna and to selectively electrically couplethe second transmission path to the antenna.
 18. The multi-band wirelessdevice 18 wherein the first transmission path includes a load impedanceof the first matching network configured to damp a resonance in thefirst transmission path due to coupling with the second transmissionpath.
 19. The multi-band wireless device 18 wherein multi-band wirelessdevice is a mobile phone.
 20. The multi-band wireless device of claim 17wherein the multi-band wireless device is configured such that thesecond transmission path is non-active when the first transmission pathis active.